Sealing mechanism for water pump

ABSTRACT

A water pump includes a pump body and a block which are respectively provided with attachment surfaces that surround an opening defined by a vortex chamber. A first one of the attachment surfaces is provided with an annular groove. An annular sealing member is embedded in the annular groove. A sealing mechanism for the water pump includes the annular sealing member having a protruding segment protruding from a periphery of the annular sealing member such that the protruding segment extends outward from an outer periphery of a second one of the attachment surfaces; and the annular groove having a branching groove segment which branches out from the annular groove and is provided in the first one of the attachment surfaces such that the protruding segment is embedded in the branching groove segment.

This application is based on and claims priority under 35 U.S.C. § 119to Japanese Patent Application 2004-131195, filed on Apr. 27, 2004, theentire content of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a sealing mechanism for a water pump.

2. Description of the Related Art

A typical water pump is disclosed in, for example, pages 3 and 4 andFIG. 1 of Japanese Unexamined Patent Application Publication No.2003-314491. In this water pump, a front portion of a pump body 12 isprovided with a cylindrical supporting section 12 b having a smalldiameter. The cylindrical supporting section 12 b rotatably supports apulley 20 via a bearing unit 14. The pulley 20 is provided with a shaft25 which extends towards the rear side of the water pump through acenter hole 26 provided in the cylindrical supporting section 12 b, suchthat a rear end portion of the shaft 25 is integrally combined with animpeller 30. The water pump also includes a block 90 whose front portionis provided with an attachment surface. The attachment surface isdepressed and thus provided with an opening functioning as a vortexchamber 95. Furthermore, the attachment surface of the block 90 is alsoprovided with an annular groove that surrounds the opening defined bythe vortex chamber 95. An annular sealing member 80 is embedded in theannular groove. The pump body 12 is fixed to the attachment surface ofthe block 90 in a manner such that the impeller 30 is housed in thevortex chamber 95 and that the annular sealing member 80 is disposedbetween the pump body 12 and the block 90. Moreover, a mechanicalsealing member 50 intervenes an inner surface of the pump body 12 facingthe vortex chamber 95 and an outer periphery surface of the rear endportion of the shaft 25.

Conventionally, an annular sealing member is provided with a protrudingsegment which protrudes from an outer periphery thereof such that theprotruding segment extends outward from the outer periphery of a pumpbody. The protruding segment is used for determining whether the annularsealing member is properly installed after a water pump is fabricated bysecurely attaching the pump body to an attachment surface of a block.Specifically, the protruding segment is embedded in a branching groovesegment which branches out from an annular groove provided in theattachment surface of the block.

Furthermore, since the block is a die-cast product formed by, forexample, aluminum die-casting, a gas-leakage test is performed in orderto inspect for casting faults, such as a cavity, in an internal waterduct and the annular groove into which the annular sealing member is tobe embedded. In order to perform such a test, a leakage-testsealing-member is embedded in the annular groove during the fabricationprocess such that the leakage-test sealing member is in contact with thebottom surface of the annular groove. While the opening of theattachment surface of the block defined by a vortex chamber is sealed,gas pressure is applied to the internal space of the block. In order toperform such a test on a large number of blocks, each leakage-testsealing member is made narrower in width than the annular groove so thatthe sealing member can be easily detached. However, the narrowleakage-test sealing member is problematic in that its life span isextremely short. Moreover, since the leakage-test sealing member is tobe embedded in the annular groove, the block must be positionedaccurately with respect to the sealing member. Furthermore, thebranching groove segment for holding the protruding segment used fordetermining the proper installation of the annular sealing memberdivides the attachment surface at an outer periphery side of the annulargroove. For this reason, the opening of the attachment surface definedby the vortex chamber cannot be sealed since the sealing member cannotbe made in contact with the attachment surface at the outer peripheryside of the annular groove. If the sealing member is made in contactwith the attachment surface at an inner side of the annular groove toseal the opening of the attachment surface defined by the vortexchamber, the annular groove cannot be inspected for casting faults.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide asealing mechanism for a water pump that allows for an easy inspectionfor faults that may be present in internal spaces of a block, such as anannular groove having a branching groove segment for holding aprotruding segment of an annular sealing member used for determining aproper installation of the annular sealing member, and a vortex chambersurrounded by the annular groove.

According to an aspect of the present invention, a sealing mechanism fora water pump is provided in which the water pump includes a pump body;an impeller rotated by driving means; and a block which forms a vortexchamber together with the pump body, the vortex chamber housing theimpeller, wherein the pump body and the block respectively haveattachment surfaces that surround an opening defined by the vortexchamber, wherein a first one of the attachment surfaces is provided withan annular groove, and wherein the pump body and the block are combinedwith each other via the respective attachment surfaces in a manner suchthat an annular sealing member is embedded in the annular groove anddisposed between the pump body and the block. The sealing mechanismincludes the annular sealing member including a protruding segmentprotruding from a periphery of the annular sealing member such that theprotruding segment extends outward from an outer periphery of a secondone of the attachment surfaces; and the annular groove including abranching groove segment which branches out from the annular groove andis provided in the first one of the attachment surfaces such that theprotruding segment is embedded in the branching groove segment. Thefirst one of the attachment surfaces has a single plane and extendscontinuously around the annular groove and the branching groove segmentin a surrounding manner.

In the sealing mechanism for the water pump, the driving means may be apulley rotatably supported by a cylindrical supporting section via ashaft bearing unit, the cylindrical supporting section being provided ina portion of the pump body, the portion being proximate one side of thewater pump. Moreover, the pulley may include a shaft extending towardsthe other side of the water pump through a center hole provided in thecylindrical supporting section such that an end portion of the shaft isintegrally combined with the impeller, the end portion being proximatethe other side of the water pump. Furthermore, the first one of theattachment surfaces may be provided in the block and the second one ofthe attachment surfaces may be provided in the pump body.

As mentioned above, according to the present invention, the pump bodyand the block respectively have attachment surfaces that surround anopening defined by the vortex chamber, and the first one of theattachment surfaces is provided with the annular groove. Moreover, theannular sealing member embedded in the annular groove is provided andhas the protruding segment protruding from the periphery of the annularsealing member such that the protruding segment extends outward from theouter periphery of the second one of the attachment surfaces.Furthermore, the annular groove includes the branching groove segmentwhich branches out from the annular groove and is provided in the firstone of the attachment surfaces such that the protruding segment isembedded in the branching groove segment. Consequently, after the waterpump is fabricated by combining the pump body and the block via therespective attachment surfaces, the protruding segment may be visuallychecked to determine whether the annular sealing member is properlyinstalled. Furthermore, since the first attachment surface has a singleplane and extends continuously around the annular groove and thebranching groove segment in a surrounding manner, a gas-leakage test canbe performed by applying gas pressure to the internal space of the blockin a state where a leakage-test sealing member is in contact with thefirst attachment surface at the outer periphery side of the annulargroove and the branching groove segment such that the internal spacesurrounded by the first attachment surface is sealed. Accordingly, aninspection process for faults in the annular groove and the internalspace can be readily performed while achieving a simple and low-coststructure. Furthermore, since the leakage-test sealing member is not tobe embedded in the annular groove, the leakage-test sealing member mayhave a large width. This achieves a longer life span of the leakage-testsealing member. Moreover, the block may be positioned roughly withrespect to the leakage-test sealing member.

In addition, since the protruding segment protruding from the peripheryof the annular sealing member may extend outward from the outerperiphery of the pump body, and the branching groove segment branchingout from the annular groove and holding the protruding segment may beprovided in the attachment surface of the block, the protruding segmentmay be visually checked to determine whether the annular sealing memberis properly installed after the water pump is fabricated by combiningthe pump body and the block via the respective attachment surfaces.Furthermore, since the attachment surface has a single plane and extendscontinuously around the annular groove and the branching groove segmentin a surrounding manner, a gas-leakage test can be performed by applyinggas pressure to the internal space of the block in a state where aleakage-test sealing member is in contact with the attachment surface atthe outer periphery side of the annular groove and the branching groovesegment such that the opening in the attachment surface defined by thevortex chamber is sealed. Accordingly, an inspection process for faultsin the annular groove and the internal space can be readily performedwhile achieving a simple and low-cost structure. Furthermore, since theleakage-test sealing member is not to be embedded in the annular groove,the leakage-test sealing member may have a large width. This achieves alonger life span of the leakage-test sealing member. Moreover, the blockmay be positioned roughly with respect to the leakage-test sealingmember.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and additional features and characteristics of the presentinvention will become more apparent from the following detaileddescription considered with reference to the accompanying drawings,wherein:

FIG. 1 is a cross-sectional view of a first type of water pump providedwith a sealing mechanism according to an embodiment of the presentinvention;

FIG. 2 mainly illustrates a section of an attachment surface of a block;

FIG. 3 mainly illustrates an annular sealing member;

FIG. 4 is a cross-sectional view of a second type of water pump providedwith the sealing mechanism according to the present invention;

FIG. 5 is a cross-sectional view of a third type of water pump providedwith the sealing mechanism according to the present invention; and

FIG. 6 is a cross-sectional view of a fourth type of water pump providedwith the sealing mechanism according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A first type of water pump 10 provided with a sealing mechanismaccording to an embodiment of the present invention will now bedescribed with reference to the drawings. In the description below, theterms “front” and “rear” respectively refer to the left and right sidesof a water pump in cross section shown in each of FIGS. 1, 4, 5, and 6.Referring to FIGS. 1 and 2, the water pump 10 includes a block 11 whichis a part of a chain case fixed to a front face of a cylinder block ofan engine. A front portion of the block 11 has an attachment surface 14to which a pump body 12 is fixed with a bolt 13. The attachment surface14 is depressed and thus provided with an opening functioning as avortex chamber 16 that houses an impeller 15. The impeller 15 rotatesand creates a centrifugal force that allows coolant water in the vortexchamber 16 to flow outward and to be pressurized. The coolant water thustravels through a water duct 19 disposed around the periphery of thevortex chamber 16 in the block 11 so as to be discharged outward from adischarge hole 18. Moreover, a rear portion of the block 11 is providedwith a suction hole 17 which communicates with the vortex chamber 16.The discharging of coolant water causes a reduction of pressure in thevortex chamber 16, whereby new coolant water is sucked in through thesuction hole 17.

A front portion of the pump body 12 is provided with a cylindricalsupporting section 20 which rotatably supports a pulley 21 via a shaftbearing unit 23. The shaft bearing unit 23 is disposed between an outerperiphery surface of the cylindrical supporting section 20 and an innersurface of a cylindrical boss 22 of the pulley 21. The pulley 21 isprovided with a shaft 24 which extends through a center hole of thecylindrical supporting section 20 towards the vortex chamber 16 in theblock 11 such that a rear end portion of the shaft 24 is engaged withthe impeller 15.

The water pump 10 further includes a mechanical sealing member 25. Themechanical sealing member 25 includes a stationary unit and a rotatableunit which perform a sliding operation in order to prevent the coolantwater from flowing forward from the vortex chamber 16. Specifically, thestationary unit is fitted to a large-diameter recess provided on therear side of the cylindrical supporting section 20 of the pump body 12,and the rotatable unit is fitted around the outer periphery of the rearend portion of the shaft 24 of the pulley 21.

Furthermore, the water pump 10 further includes a cylindrical cover 26provided with a base surface. The cylindrical cover 26 is fixed to thepulley 21 such that the base surface of the cylindrical cover 26 coversthe front side of the cylindrical boss 22 of the pulley 21. A section inthe outer periphery of the cylindrical cover 26 is provided with afixing segment 27 which axially extends towards the rear side of thewater pump 10. A rear end portion of the fixing segment 27 is providedwith a claw which is engaged with a hole provided in a wall portion ofthe pulley 21, whereby the cylindrical cover 26 is fixed to the pulley21. Specifically, the wall portion extends between the cylindrical boss22 and a belt hanging portion 28 defining the outer periphery surface ofthe pulley 21. The center of the cylindrical cover 26 is provided with acentral shaft extending towards the rear side of the water pump 10 andhaving a slit extending in the axis direction of the central shaft. Thecentral shaft is resiliently fitted in a shaft hole provided in theshaft 24 of the pulley 21 so as to block the shaft hole.

The attachment surface 14 of the block 11 is provided with an annulargroove 29 which surrounds the opening in the attachment surface 14defined by the vortex chamber 16 and the water duct 19. The pump body 12is fixed to the attachment surface 14 via the bolt 13 in a manner suchthat the impeller 15 is housed in the vortex chamber 16 and that anannular sealing member 31 (see FIG. 3) embedded in the annular groove 29is disposed between an attachment surface 34 of the pump body 12 and theattachment surface 14 of the block 11. The annular sealing member 31 hasa protruding segment 32 protruding from the periphery thereof, such thatthe protruding segment 32 extends outward from the outer periphery ofthe pump body 12 or the attachment surface 34. The attachment surface 14is provided with a branching groove segment 33 that branches out fromthe annular groove 29 such that the protruding segment 32 is embedded inthe branching groove segment 33. The attachment surface 14 has a singleplane and extends continuously around the annular groove 29 and thebranching groove segment 33 in a surrounding manner. Consequently, theopposite sides of the entire annular sealing member 31 are respectivelypressed by the bottom surface of the annular groove 29 and theattachment surface 34 of the pump body 12. Thus, the vortex chamber 16and the water duct 19 surrounded by the annular groove 29 and definingthe opening in the attachment surface 14 are sealed from the outside.Furthermore, by visually checking that the protruding segment 32properly extends outward from the outer periphery of the pump body 12 orthe attachment surface 34, it can be confirmed that the annular sealingmember 31 is properly installed.

In order to inspect for faults in the block 11, such as a cavity, duringa manufacturing process, a leakage-test sealing-member may bepressure-bonded to the attachment surface 14 extending continuouslyaround the annular groove 29 and the branching groove segment 33. Inthis case, while the internal spaces of the block 11, such as theannular groove 29, the vortex chamber 16, and the water duct 19, aresealed, gas pressure is applied to the internal spaces so that theannular groove 29 and the internal spaces in the block 11 can beinspected for faults.

When the pulley 21 is rotated by a belt hung between a pulley engagedwith an end of a crankshaft of the engine and the belt hanging portion28 of the pulley 21, the impeller 15 engaged with the shaft 24 of thepulley 21 is accordingly rotated. Specifically, the pulley engaged withthe end of the crankshaft of the engine, the pulley 21, and the belthung between the two pulleys, for example, define driving means 35 forrotating the impeller 15.

A pumping action generated in response to the rotation of the impeller15 allows the coolant water in the vortex chamber 16 to flow outward andbe pressurized due to a centrifugal force. The coolant water thustravels through the water duct 19 so as to be discharged outward fromthe discharge hole 18. The discharging of the coolant water causes areduction of pressure in the vortex chamber 16, whereby new coolantwater is sucked in through the suction hole 17.

Water pumps of second to fourth types each provided with the sealingmechanism according to the present invention will now be described withreference to FIGS. 4 to 6, respectively. The sealing mechanism is thesame as that provided in the first type of water pump 10, and therefore,the corresponding components are given the same reference numerals, anddetailed description of such components will be omitted below to preventredundancy.

FIG. 4 illustrates a second type of water pump 40 which is amagnetically-driven pump. The water pump 40 includes a block 41 which isa front end portion of a cylinder block of an engine. A front portion ofthe block 41 has an attachment surface 14 to which a pump body 42 isfixed with a bolt. The attachment surface 14 is depressed and is thusprovided with an opening functioning as a vortex chamber 46 that housesan impeller 45. The attachment surface 14 is provided with an annulargroove 29 which surrounds the opening in the attachment surface 14defined by the vortex chamber 46. An annular sealing member 31 isembedded in the annular groove 29 and is disposed between the attachmentsurface 14 of the block 41 and an attachment surface 34 of the pump body42.

The water pump 40 further includes driving means 47 for rotating theimpeller 45. The driving means 47 includes a pulley sheet 48 integrallyconnected with a pulley to which a torque from the engine istransmitted, and a driving shaft 50 rotatably supported by the pump body42 via a bearing unit 49. The pulley sheet 48 and the driving shaft 50are combined with each other. A driving magnet unit 52 has a magnet 51fixed thereto and is attached to the driving shaft 50. A wall portion 53is disposed within an inner surface of the pump body 42. An outerperiphery of the wall portion 53 is provided with a sealing member 54which separates the vortex chamber 46 from a space 55 formed inside thepump body 42. A supporting shaft 56 is secured to the block 41 and thewall portion 53, and rotatably supports a shaft unit 44 via a submergedbearing unit 43 at a side of the wall portion 53 proximate the vortexchamber 46. Specifically, the shaft unit 44 is engaged with the impeller45, and is provided with an induction coil 57 at a position facing themagnet 51.

Accordingly, when the engine rotates the pulley sheet 48 via the pulley,the magnet 51 is correspondingly rotated, whereby an induction currentis generated in the induction coil 57. A magnetic force generated inresponse to this current and the magnetic force of the magnet 51 allowthe torque of the pulley to be transmitted to the impeller 45.Consequently, the impeller 45 is rotated, and a pumping action generatedin response to this rotation allows coolant water to be sucked into thevortex chamber 46 through a suction hole and then be discharged outwardfrom a discharge hole.

FIG. 5 illustrates a third type of water pump 60 which is anelectric-motor-driven pump. The water pump 60 includes a pump body 62and a block 61 which are combined with each other via respectiveattachment surfaces 14 and 34. In the block 61, the attachment surface34 is depressed and thus provided with an opening functioning as avortex chamber 66 that houses an impeller 65. On the other hand, theattachment surface 14 of the pump body 62 is provided with an annulargroove 29 which surrounds the opening in the attachment surface 34defined by the vortex chamber 66. The block 61 is securely combined withthe pump body 62 in a manner such that an annular sealing member 31embedded in the annular groove 29 is disposed between the block 61 andthe pump body 62. The annular sealing member 31 has a protruding segment32 protruding from the periphery thereof, such that the protrudingsegment 32 extends outward from the outer periphery of the block 61. Theattachment surface 14 of the pump body 62 is provided with a branchinggroove segment 33 that branches out from the annular groove 29 such thatthe protruding segment 32 is embedded in the branching groove segment33. The attachment surface 14 has a single plane and extendscontinuously around the annular groove 29 and the branching groovesegment 33 in a surrounding manner.

An electric motor 68 defining driving means 67 for rotating the impeller65 includes a magnet 69 fixed to a shaft 64, and an electric-wire coil70 wound around the magnet 69. In the water pump 60, the electric motor68 rotates the impeller 65 engaged with the shaft 64 inside the vortexchamber 66 formed by the pump body 62 and the block 61.

FIG. 6 illustrates a fourth type of water pump 80, which is similar tothe first type in that the water pump 80 is driven with a pulley. Thewater pump 80 includes a block 81 which is a front end portion of acylinder block of an engine. An attachment surface 14 of the block 81 isfixed to an attachment surface 34 of a pump body 82 formed by aluminumcasting via a bolt. The attachment surface 34 of the pump body 82 andthe attachment surface 14 of the block 81 are respectively provided withdepressions which together define a vortex chamber 86. The attachmentsurface 14 of the block 81 is provided with an annular groove 29 whichsurrounds an opening defined by the vortex chamber 86. The pump body 82is securely combined with the block 81 in a manner such that an annularsealing member 31 embedded in the annular groove 29 is disposed betweenthe pump body 82 and the block 81. A cylindrical section of the pumpbody 82 rotatably supports a shaft 84 via a bearing unit 83. The shaft84 is engaged with a pulley 87. A rear end portion of the shaft unit 84is engaged with an impeller 85 inside the vortex chamber 86, such thatthe impeller 85 can be rotated by the pulley 87.

1. A sealing mechanism for a water pump comprising: a pump body; an impeller rotated by driving means; and a block which forms a vortex chamber together with the pump body, the vortex chamber housing the impeller, wherein the pump body and the block respectively have attachment surfaces that surround an opening defined by the vortex chamber, wherein a first one of the attachment surfaces is provided with an annular groove, and wherein the pump body and the block are combined with each other via the respective attachment surfaces in a such manner that an annular sealing member is embedded in the annular groove and disposed between the pump body and the block, wherein the sealing mechanism comprises: the annular sealing member including a protruding segment protruding from a periphery of the annular sealing member such that the protruding segment extends outward from an outer periphery of a second one of the attachment surfaces; and the annular groove including a branching groove segment which branches out from the annular groove and is provided in said first one of the attachment surfaces such that the protruding segment is embedded in the branching groove segment, wherein said first one of the attachment surfaces has a single plane and extends continuously around the annular groove and the branching groove segment in a surrounding manner.
 2. The sealing mechanism for the water pump according to claim 1, wherein the driving means comprises a pulley rotatably supported by a cylindrical supporting section via a shaft bearing unit, the cylindrical supporting section being provided in a portion of the pump body, the portion being proximate one side of the water pump, and wherein the pulley includes a shaft which extends towards the other side of the water pump through a center hole provided in the cylindrical supporting section such that an end portion of the shaft is integrally combined with the impeller, the end portion being proximate the other side of the water pump.
 3. The sealing mechanism for the water pump according to claim 1, wherein said first one of the attachment surfaces is provided in the block and said second one of the attachment surfaces is provided in the pump body.
 4. The sealing mechanism for the water pump according to claim 2, wherein said first one of the attachment surfaces is provided in the block and said second one of the attachment surfaces is provided in the pump body. 